Shimano Ultegra 6600 10 Speed CassetteDesigned for high performance 10-speed road bikes, mainly aimed at racing juniors and lower teeth. The hyperglide sprockets have been specially computer designed to create a specific configuration that results in a smooth shift even when under high impact.FeaturesWeighs 235gDesigned for super narrow 10 speed HG chainsSprockets cut away and drilledReduced weightClose ratio gearingBuy Shimano Components from Chain Reaction Cycles, the World's Largest Online Bike Store.